1. Field of the Invention
This invention relates generally to the field of cooling of components in turbocharger systems and, more particularly, to an ejector entrainment arrangement for drawing cooling air through components of the turbocharger for operating temperature reduction.
2. Description of the Related Art
Turbocharger systems are rapidly evolving for higher performance. Novel bearing systems such as air bearings and supplemental energy devices such as electrical motor systems for accelerating turbine and compressor rotors in low exhaust energy states are being developed for increasing range and performance of current turbochargers. These systems often require temperature regulation for efficient operation. The relatively high operating temperatures of turbocharger components provide minimal availability of conductive heat reduction. Water jacketing systems have been used with some success in reducing operating temperatures of conventional bearings, however, liquid cooling systems require complex casting, machining and sealing technologies for implementation. In addition, current engine systems are operating at the upper limits of heat load rejection without undesirable increases in sizing of cooling heat exchanger components and addition of more cooling requirements may not optimize the overall engine cooling system.
It is therefore desirable to provide alternative cooling methods for new turbocharger components which limit operational impact on current engine heat exchanger components.
Additionally, a system for providing cooling flow to a turbocharger device is desirable with the ability to support compressor operation all the way from choke to surge, and from low to high shaft speeds.
Further, cleanliness of the provided cooling flow is required to avoid any possible harmful contamination or startup problems and a compact system with minimum impact on the engine overall performance is desirable.
The present invention provides a turbocharger component cooling system using an ejector having a primary inlet, a secondary inlet and an outlet. An energizing gas conduit connects a first bleed port from a high energy gas source and the primary inlet of the ejector. A cooling gas conduit connects a coolant inlet to a component cooling plenum and then connects the cooling plenum to the secondary inlet of the ejector. An outlet gas conduit connects the ejector outlet to a low pressure dump. In one embodiment, the energizing gas source is the output of the turbocharger compressor while in a first alternative embodiment, the energizing gas source is the exhaust gas inlet to the turbocharger. For these embodiments, the low pressure dump is the compressor inlet and the turbine exhaust gas outlet, respectively.